1. Field of the Invention
The present invention relates to forced-air heaters and more particularly, to portable forced-air heaters which use fewer components and are simple to assemble. According to a preferred embodiment, both the base and outer shell are formed as a unichassis from a single sheet of pre-painted metal, while the combustion chamber is formed of a single sheet of a second sheet of metal. Aligning tabs and brackets are formed as an integral part of both the unichassis and the combustion chamber. Further, disruption and/or deformation of the metal forming the unichassis and the combustion chamber is used to fasten metal to metal and to retain one component in a pre-determined position with respect to a second component.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Portable forced-air heaters which typically burn fuels such as kerosene and preferably propane are used extensively at construction sites and outdoor sporting events. They are lightweight, easy to carry, and are unusually safe considering the significant amount of heat they can provide almost instantaneously.
However, although rather simple in concept, presently available heaters use a large number of components which must be assembled and consequently, increase the cost to manufacture the heater. Furthermore, because of the amount of heat provided and operation of the heaters in close proximity to people in combustible building materials, it is extremely important that the outer shell remain cool enough to touch without danger, and that the support surface (e.g. the floor) for the heater (which may be combustible) must not be subjected to excessive heat. Therefore, these portable heaters typically use a flow of unheated air to maintain safe operating conditions. For example, a flow of unheated air is directed onto the floor or support surface to avoid overheating. In addition, a flow of air is provided between the outer shell of the heater and the combustion chamber to maintain the temperature of the outer shell safe to touch. To maintain a properly-directed and continuous flow of air, the location of the heater components with respect to each other is very important. Consequently, because of the large number of components that must be carefully assembled, the labor costs for manufacturing is significant.
A typical prior art portable heater is disclosed in U.S. Pat. No. 5,848,585 to Norris R. Law and Clyde R. Schulte.